1. Field of the Invention
This invention relates to electric lamps and has particular reference to an improved incandescent lamp of the reflector type and to a method of providing such lamps with an exterior light-reflective coating.
2. Description of the Prior Art
Electric lamps which employ a gaseous discharge or an incandescent filament as a light source and have an envelope that is partly coated with a light-reflective material which controls the light rays are well known in the art. In the case of reflector lamps of the incandescent type, the integral reflector usually comprises a thin coating of a metal such as aluminum, silver, etc. that is deposited on the inner or outer surface of the bulb either by a wet-coating process or by vacuum deposition techniques utilizing vaporized metal. While the prior art coating methods produced reflective coatings that were satisfactory, they were slow and quite costly and provided optimum results when used to coat lamp envelopes before they were sealed and made into finished lamps. When they were employed to reflectorize the bulbs of finished lamps, such processing was generally not performed by the lamp manufacturer but by an outside vendor who specialized in that art. This necessitated shipment of the fabricated lamps to and from the vendor--a very inefficient and costly arrangement since it required careful handling of the lamps and inherently complicated production and shipment schedules due to the long lead times needed to get the lamps coated and returned to the factory.